0.4.0 — Delivery observation

Minor release target: retain #69/#70/#71/#72 together. User-approved 2026-10-11 scope is the frozen shared handoff contract, narrowly qualified macOS arm64 Codex client-ID observation, bounded app-server/SSH transport and explicit operator-confirmed receipts. Linux observation #130, Windows observation/private storage #131 and voluntary authenticated receipt producer/collector bootstrap #132 are Future extensions. Unsupported required goals refuse before effect; no automatic resend, dedup or exactly-once claim. Companion guidance and human review/current-main checks remain gates. No publication approval is implied.